Regiodivergent Synthesis of ortho- and para-Cannabinoquinones

Spurred by the remarkable biological profile of cannabinoquinoids, we have systematically investigated the periodinane oxidation of their resorcinolic precursors, discovering that the regiochemistry of oxidation, a critical maneuver for bioactivity, depends not only on the nature of the oxidant (lambda(3)- vs. lambda(5)-iodanes), but also on post-oxidative prototropic- and valence tautomeric equilibria that isomerize ortho-quinones to para-quinones. By complementary selection of the periodinane oxidant and by freezing prototropic equilibration with O-methylation, isomeric ortho- and para-quinones could be obtained from mono- and diphenolic cannabinoids, setting the stage for the exploration of novel areas of the biological space, and establishing a blueprint for the extension of this strategy to other classes of bioactive alkylresorcinols.